Liquid-gas contactor

ABSTRACT

A liquid-gas contactor in which one or more cylindrical screens constantly revolve about their axes, with their lower periphery dipping into the liquid so that films of the liquid are constantly carried thru an atmosphere of reactant gas which is maintained above the liquid. The cylindrical screens may be of respectively decreased diameter, arranged one internally within the other, and the inner screens may rest on the inner surface of the outer larger diameter screen so that it rotates therewith by rolling contact.

Elite States Patent Barnes, Jr. et al.

[ 51 Aug. 15,1972

LIQUID-GAS CONTACTOR [72] Inventors: Vernon M. Barnes, Jr., Richmond;Rudolph C. -White, Midlothian, both of Va.

[73] Assignee: Texaco Inc., New York, NY.

[22] Filed: July 6, 1970 [21] App1.No.: 52,225

52 US. Cl ..261/92 [51] Int. Cl. ..B0lf 3/04 [58] Field of Search..261/92, 83

[56] References Cited UNITED STATES PATENTS 2,440,446 4/1948 Kenny..261/92 1,826,508 10/1931 Decker ..261/92 3,306,591 2/1967 Valazza..261/92 3,021,831 2/1962 Byrge ..261/92 3,353,337 11/1967 Gale ..261/923,442,495 5/1969 Schreiber ..261/92 FOREIGN PATENTS OR APPLICATIONS9,922 8/1907 Denmark ..261/92 OTHER PUBLICATIONS German Printed Appl.No. 1,187,587 Kunze et al. 8/17/61.

Primary ExaminerTim R. Miles Attorney-Thomas H. Whaley, Carl G. Reis andL. H. Phelps, Jr.

[57] ABSTRACT A liquid-gas contactor in which one or more cylindricalscreens constantly revolve about their axes, with their lower peripherydipping into the liquid so that films of the liquid are constantlycarried thru an atmosphere of reactant gas which is maintained above theliquid. The cylindrical screens may be of respectively decreaseddiameter, arranged one internally within the other, and the innerscreens may rest on the inner surface of the outer larger diameterscreen so that it rotates therewith by rolling contact.

8 Claims, 4 Drawing Figures PATENTEDAUB 15 I972 SHEET 1 BF 2 FIG.

LIQUID-GAS CONTACTOR The present invention relates to a liquid-gascontac tor and particularly to the absorption or reaction of a gas by orwith a liquid.

ln chemical processes involving relatively slow absorption or reactionof a liquid and a gas, such as the so-called hydrogenation, for example,of a petroleum product, progress of the absorption or reaction, as thecase may be depends upon the area of surface contact between theun-reacted liquid and the gas.

Reference herein to relatively slow rates of reaction or absorptionmeans actions wherein the gas is progressively absorbed or reacted withthe liquid at the interface and at a rate requiring excellent andsomewhat prolonged contact.

Also the words reactant gas" or liquid, as the case may be, or toabsorption or reaction of said constituents, refer not only to theinteraction of such materials which respectively enter into chemicalreaction with each other but to those which are desirably absorbed oradsorbed to form a desirable combined product.

Among the multiplicity of the devices heretofore proposed foraccomplishing such contact, possibly the most common are packed columnsor towers in which the liquid flows downwardly through a relativelyelevated column usually occupied by a packing of particles or elementsof various shapes to break up and distribute the flow of liquid in anupcoming flow of gases. Another variation of this is the tray towerwhich conducts a gravity flow of the liquid in thin layers through aseries of trays ordinarily including liquid falls or sprays, again in anatmosphere of reactive gases.

The shortcomings of such systems have been widely demonstrated andaccepted.

The present invention, on the other hand, involves a rotary reactorinvolving one or more preferably cylindrical members which continuouslydip into the liquid and convey it in thin films through, and in contactwith, an atmosphere of reactant gases. Preferably the cylindricalmembers are selected to carry thin, highly exposed films of liquid whicheven during rotation tend to drain downwardly and expose fresh surface.

This has the advantage of constantly exposing surfaces of unreactedliquid and thus promoting more or less uniform exposure and interactionof the reactants at fresh interfaces and under readily predeterminableparameters so that the design may accurately accord with therequirements of the system.

More specifically, in order to explain the invention in greater detailand to illustrate the features of the present invention, reference ismade to the attached figures of the drawing wherein FIG. 1 is atransverse vertical section taken through a reactor constructed inaccordance with the present invention,

FIG. 2 is a vertical section taken on the line 22 of FIG. 1,

FIG. 3 is a transverse vertical section taken axially through a somewhatmodified form of reactor, and

FIG. 4 is a transverse vertical section taken on the line 44 of FIG. 3.

Referring to FIGS. 1 and 2, the numeral represents a cylindrical housing10 closed at one end by curved wall 12, carrying bearing 14. Theopposite extremity of the tubular housing 12 is enclosed by plate 16which carries bearing 18, preferably provided with a rotary shaft sealnot shown. The plate 16 may he releasably secured to the housing 10 bysuitable fasteners 20. A suitable supply of liquid reactant is furnishedto the housing 10 via inlet 22, being withdrawn through liquid outlet24.

Suitable means, not shown, is preferably provided to maintain a constantlevel of liquid 26 within the reactor. In this case such means iscontrolled by liquid level float 28.

Obviously, in view of the foregoing, a suitable weir or riser may beassociated with outlet 24 to accomplish this purpose.

In operation the liquid is continuously picked up on nested cylinders30, 32 and 34 which are continuously rotated, with the lower partscontinuously dipping into, and being immersed in the liquid.

This is effected by virture of the fact that the outermost cylinder 30is mounted upon shafts 36 and 38 which rotate in the foregoing bearings18 and 14 respectively, the shafts being, in turn, coaxially attached tothe extremities of cylinder 30 by means of suitable spider elements 40.These may. for example. comprise angularly spaced, radial arms whichpermit the free access of gas to the central portion of the cylinders aswill hereinafter be more fully explained.

Accordingly therefore, with the foregoing construction, the internal andsmaller diameter cylinders 32 and 34, nested within the cylinder 30,rest on the bottom thereof and as the cylinder 30 rotates, the other twocylinders are accordingly carried by it in the same rotationaldirection, but as will hereinafter appear, at significantly differentangular rates of revolution.

It is to be noted that the outer cylinder 30 preferably has at its axialextremities, inwardly projecting annular flanges 42 to confine the innercylinder or cylinders as the case may be. Corresponding annular flanges44 may be provided on the inner tubes or cylinders 32 and 34 ifdesirable or necessary although minimization of the size and extent ofthese annular members is usually advisable to permit free access of gasto the interior thereof. In brief, therefore, the shafts 36 and 38support and drive the outer cylinder about its axis so that itcontinuously dips into the liquid reactant while the internally nestedscreens simply roll thereon. As a result the screens continuously carryfilms of liquid upwardly through arcuate paths.

Not only the liquid but the gas likewise may be admitted through inletpipe 22, no outlet being necessary for a gas of the type which can beand is completely consumed or absorbed by the so-called reactant liquid.On the other hand, gas outlet can be added if it is desired to removegaseous product or to recycle the gas.

Thus in the hydrogenation of a liquid hydrocarbon, for example, theliquid is preferably introduced through pipe 22 and retained for apredetermined period of time at a predetermined depth in the tube 10 bymeans of level control means previously mentioned.

Accordingly, during this period, the shaft 36 is continuously rotated bydrive means not shown, to rotate the three cylinders 30, 32 and 34, eachof which is continuously dipping into the liquid at its lower face andcarrying a thin layer upwardly through the rotational path into and incontact with the surrounding atmosphere of hydrogen gas likewisecontinuously introduced through 22.

It is to be particularly noted that in addition to the thin film andhigh exposure area of contact thus effected, the several cylindersrotate at significantly different rates of revolution. This thereforemeans that, at least in the open spaces between the top sections of thevarious cylinders, the surfaces are moving at substantial disparaterotational velocities to effect a constant shearing effect on thegaseous atmosphere, and thereby to avoid what engineers refer to as theskin effect and to constantly present fresh contact surface. Theseeffects are improved by the fact that there is usually an inherentdrainage going on from the upper surface of the rotating cylinderdownwardly toward the lower pool of liquid 26.

To enhance the foregoing effect it is preferred to provide cylinders ofroughened or reticulated material such as embossed metal or screening.Wire screening, for example, has the inherent advantage of enabling thepresentation of fine films between the reticulations of the screen.

In addition it enables optimum design correlation between the aperturesize of the screen and the particular viscosity characteristics of theliquid, for example, to effect a closely controlled rate of filmexposure.

A modified form of the foregoing embodiment shown in FIGS. 3 and 4comprises a reactor which is per se rotated about its axis by spaceddrive rolls 46 continuously driven in the same rotational direction byshaft 48. The rollers 46, as shown, form a cradle upon which the tubularreactor turns. This accordingly avoids the necessity for driving thecylinders 30, 32 and 34 which simply rest upon the inner, lower surfaceof the tube 10 and are rotated by rolling thereon.

Nevertheless, essentially the same result is achieved as in the earlierembodiment, namely the continual rotation of the preferably reticulatescreens so as to dip into and pick up films of reactant liquid and tocarry it upwardly at different rates through an atmosphere of reactantgas.

In the present embodiment the gas and liquid reactants are preferablyintroduced by inlet tube 50 through an axially disposed fixture mountedwithin a rotary swivel joint bearing or seal 52. The inlet tube maydischarge into any portion of the reactor as shown, preferably beyond anannular baffle or weir 54.

An appropriate liquid level within and about the screen cylinders ismaintained by annular weir 56 near the opposite extremity of the reactortube. The treated liquid is withdrawn from a sump just beyond weir 56 bya pipe 58 and an appropriate suction pump, not shown. The pump may beoperated in response to liquid level control flow 60.

Where the contactor is operated under pressure, the level control willoperate a valve instead of pump since the main purpose of the levelcontrol in such event is to avoid loss of gas.

The present invention thus provides a reactor which is readily operableat reasonable predetermined temperatures and pressures and is alsocapable of enabling specifically controlled and predetermined exposureof the reactants. For example, the screens operate within a col ofliquid of controlled and predetermined v0 ume which passes through thesystem at a specifically controlled rate.

The residence time of the liquid is the function of dynamic liquidcapacity and feed rate. Furthermore, each liquid particle actuallydescribes a helix as it is successively exposed to the reactant gaswhile migrating from inlet to outlet.

We claim:

1. A liquid gas reactor comprising an elongated fluid holding housingdefining an enclosure therein,

means for passing a stream of liquid through said housing and formaintaining a pool of said liquid in the housing lower section,

means for introducing a gaseous medium into said housing whereby tomaintain an atmosphere of said medium within the housing,

a plurality of cylindrical members disposed longitudinally of saidhousing and being at least partially immersed in said pool of liquid,said respective cylindrical members being nested one within the other,the inner of said cylindrical members being supported by the nextadjacent outer member, and

means for rotating the outermost of said cylindrical members whereby therespective inner cylindrical members will be rotated at a greater speedthan said outer member.

2. A liquid gas reactor as defined in claim 1, wherein said cylinder ischaracterized by an irregular external surface.

3. A liquid gas reactor as defined in claim 1, wherein said respectivecylindrical members are formed of reticulated material.

4. In a liquid gas reactor as defined in claim 1, including; drive meansengaging said outer cylindrical member and operable to rotate said outermember.

5. In a liquid gas reactor as defined in claim 1, including; a driveshaft journalled longitudinally of said housing and supporting the outerof said cylindrical members, and means for rotating said drive shaftwhereby to rotate said outer cylindrical member.

6. In a liquid gas reactor as defined in claim 1, including; float meansdisposed within said housing and being operable to regulate the level ofliquid maintained in said pool.

7. In a liquid gas reactor as defined in claim 1, including; bearingmeans rotatably supporting said elongated housing, and means forrotating said housing on said bearing means.

8. In a liquid gas reactor as defined in claim 7, wherein the outer ofsaid cylindrical members is supportably positioned at the inner wall ofsaid housing whereby said inner cylindrical member is rotated inresponse to rotations of said housing.

1. A liquid gas reactor comprising an elongated fluid holding housingdefining an enclosure therein, means for passing a stream of liquidthrough said housing and for maintaining a pool of said liquid in thehousing lower section, means for introducing a gaseous medium into saidhousing whereby to maintain an atmosphere of said medium within thehousing, a plurality of cylindrical members disposed longitudinally ofsaid housing and being at least partially immersed in said pool ofliquid, said respective cylindrical members being nested one within theother, the inner of said cylindrical members being supported bY the nextadjacent outer member, and means for rotating the outermost of saidcylindrical members whereby the respective inner cylindrical memberswill be rotated at a greater speed than said outer member.
 2. A liquidgas reactor as defined in claim 1, wherein said cylinder ischaracterized by an irregular external surface.
 3. A liquid gas reactoras defined in claim 1, wherein said respective cylindrical members areformed of reticulated material.
 4. In a liquid gas reactor as defined inclaim 1, including; drive means engaging said outer cylindrical memberand operable to rotate said outer member.
 5. In a liquid gas reactor asdefined in claim 1, including; a drive shaft journalled longitudinallyof said housing and supporting the outer of said cylindrical members,and means for rotating said drive shaft whereby to rotate said outercylindrical member.
 6. In a liquid gas reactor as defined in claim 1,including; float means disposed within said housing and being operableto regulate the level of liquid maintained in said pool.
 7. In a liquidgas reactor as defined in claim 1, including; bearing means rotatablysupporting said elongated housing, and means for rotating said housingon said bearing means.
 8. In a liquid gas reactor as defined in claim 7,wherein the outer of said cylindrical members is supportably positionedat the inner wall of said housing whereby said inner cylindrical memberis rotated in response to rotations of said housing.